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Computer Science IGCSEPDF 33
142 pagesrevision 46930
PDF 33
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Faster access speeds up operations like the Fetch-Execute
Cycle.
It holds data and instructions the CPU needs while the
computer is on.
Acts as short-term, working memory.
Includes RAM, cache, and registers directly connected to
the CPU.
High performance makes it expensive, so capacity is
limited.
RAM
Random Access Memory
RAMis primary storage directly connected to CPU.
Holdsdata and instructions currently in use.
RAMis volatile, so data is lost when power is off.
Dataand instructions are copied from secondary storage for
theCPU to use.
RAMis very fast, much quicker than secondary storage.
Itisread/write, meaning data can be read and written.
RAMhas a much larger capacity than ROM.
ROM
ROM (Read Only Memory) is primary storage that stores
startup instructions (Bootstrap). It contains the BIOS
(Basic Input Output System). ROM is a small memory
chip on the motherboard. It is fast—faster than
secondary storage but slower than RAM. ROM is non-
volatile, so data is kept when power is off. Itis read-only,
meaning data can only be read. ROM has a much smaller
capacity than RAM.
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